Grinding gauge for out-of-round pistons



March 15, 1949. s, FOSTER v 7 2,464,387

GRINDING GAUGE FOR OUT-OF-ROUND PISTONS Filed Aug. 13, 1947 w 2Sheets-Sheet l INVENTOR.

March 15, 1949. s. A. FOS TIERY 2,464,387

GRINDING GAUGE FOR OUT-OF-ROUND PISTONS v Filed Aug. 13 1947 2 Sheets-Shee t 2 I I mroKNE).

Patented Mar. 15, 1949 GRINDING GAUGE FOR OUT-OF-ROUND PISTONS Shubel A.Foster, Pleasant Ridge, Mich.

Application August 13, 1947, Serial No. 768,359

7 8 Claims.

This invention relates to gages for production grinding, wherein thegaging or checking of the work is done throughout the grinding operationso that simple observance of the progressive movement of an indicatorwill show when the grinding is completed to the extent desired,whereupon the machine may be stopped either manually, or automaticallyas by the closing of a machine-controlling circuit, and a new piece ofwork substituted for that which has just been ground.

Such type of production checking gage is now well known in the grindingindustry and has proved both fast and reliable; so that it is an objectof the present invention to utilize the advantages of such productiontype of checking gages under circumstances which have not heretoforelent themselves readily to gaging in the manner referred to, as in thecase of work which is intentionally to be ground to an out-of-round,eccentric, oval, elliptical, or similar form wherein the radialdimensions are required, nevertheless, to be accurately assured in thefinished work.

A typical example of work, to which the present invention is eminentlyadaptable, is the presenttype of piston wherein it is a common practiceto make the piston wider across one diameter than across anotherdiameter transverse to the first in order that the piston, in use, mayaccommodate itself to variations in expansion along these two diametersand thus, when heated, more correctly fit and bear on the walls of itscylinder. Generally speaking, the major of these diameters extends inalignment with the piston pin and the minor diameter at right angles tothe said pin.

The type of production gage heretofore referred to is characterized b acaliper frame engaging beneath the work and carrying, in a tubeextending upwardly of the said frame, a movable gage rod the lower endof which through the medium of a suitable wear-resisting element ridesupon the top of the work; the said gage rod being connected with anindicator adapted to show the extent of movement of said rod toward theaxis of rotation of the work and thus indicate the progress of thegrinding of the work, and/or a circuit controlling switch adapted toterminate the grinding operation when the grindingreaches the point ofcompletion. The gaging device generally described (including the caliperframe, the gage rod, its tube, and indicator) is usually carried by a.spring-mounted swinging arm suitably positioned on the grinding machinewhereby the gage may be quickly swung into and out of gaging position.

It will be clear that with such an arrangement it would be possible togage major, minor, or other diameters of the work during grinding if theindicator were constantly and closely watched and the work were rotatedat quite slow speed, but the disadvantages and limitations of gaging thework in this manner will be obvious; and the principal object of thepresent invention is to provide an arrangement, in such a type ofproduction gage, which will eliminate confusing and unnecessary gagingof all of the peripheral surface of the work except certain points whichwill be sufilcient to properly indicate the progress of the grinding.

Such point (or points) could be conveniently the high points of majordiameter, or they could be the low points of minor diameter, (or evenany given points therebetween) due to the fact that the out-of-roundform to be ground is a result of mechanical and timed manipulation ofthe grinding machine itself and is always according to pre-deterrninedpattern which may be controlled by a master cam. The means of producingthe out-of-round form is, of course, no part of the present invention.

A further object of the said invention is to provide, in a productiongrinding gage of the type referred to, means for rendering the gage-rodor element inactive throughout the greater portion of the grinding cycleand to further pro- Videfor presenting moving or permitting the gage rodor element to move into gaging relation to the work periodically and attimed intervals, whereby a certain point, or points, of determineddiameter will be regularly checked during rotation and grinding of thework.

Still further objects or advantages additional or subsidiary to theaforesaid objects, or resulting from the construction or operation ofthe invention as it may be carried into effect, will become apparent asthe said invention is hereinafter further disclosed.

In carrying the said invention into efiect, I may adopt the novelconstruction and arrange ment of parts hereinafter described, by way ofexample, having reference to the accompanying drawings, wherein:

Figure 1 illustrates a production grinding gage embodying the saidinvention as applied to a piston being ground;

Figure 2 is a detail elevation of the caliper frame and associated partsof the device shown in work-engaging position, the cam follower beingomitted for simplified illustration;

Figure 3 is a side elevation of the arrangement shown in Figure 2 butincluding the cam follower;

Figure 4 is a similar view to Figure 2 with the caliper and associatedparts removed to disclose details of the cam and follower mechanism; and

Figure 5 is a plan of the said follower and the movable jaw of thecaliper frame, the said frame being shown in section taken on a planeindicated by the line 55 in Figure 2.

Similar characters of reference indicate similar parts in the severalfigures of the drawings.

It] indicates the headstock of a grinding machine and II is an adaptoror carrier for the work, which work in this case is a piston 12, thesaid adaptor being shown as including a cam element [3 tapered at itsouter end, as at 14, to enter and locate the skirt of the piston, and adriver E5 in the form of a bifurcated extension to engage the piston pinl6 in the manner which will be quite clear to those familiar with thegeneral grinding art.

It is common to make such pistons oval or out-of-round as indicated inFigure 2 wherein a and b indicate the major and minor diameters which itis intended to grind. The outer end of the piston is usually engaged bya tailstock center (not shown).

The actual grinding of such a piston by the grinding wheel H iscontrolled by a profiling mechanism (not shown) usually involving amaster cam which causes the grinding wheel to move inwardly of the work,or the work inwardly of the grinding wheel, twice during each revolutionof the work so that the dimensional relationship of the major and minordiameters is preset; and it is not a function of the production gageabout to be described to determine this diameter variation but merely todetermine when the grinding has progressed to the finish point wherein apredetermined dimension is secured at a given point in the circumferenceof the work or piston.

It is convenient to select the high point or points for this purpose,conforming in the illustrated example to the major diameter a.

The gaging device illustrated is characterized by a C-shaped caliperframe 53 provided with a lower shoe 19 to engage beneath the work, asshown, and a laterally disposed shoe 20 to abut one side of the work andthus determine the position of the shoe l3 beneath the work. Extendingupwardly from the said caliper frame 18 is a tub-e 2| carrying avertically reciprocal gage rod 22 which is biased downwardly by acompression spring 23 in the gage head 24.

The upper end of the said rod 22 is notched to provide a shoulder 25which abuts the plunger 23 of an indicator 2'! for the operation of thesaid indicator in the manner well known. Details of the indicator itselfare not shown or described as being simply a standard mechanism Wellunderstood in the art to which this invention appertains, except to saythat the indicator illustrated is provided with a plunger extension 2 8of the type described in applicants United States Patent No. 2,270,728granted January 20, 1942, the said extension 28 passing between frictionor braking members 29 hearing on opposite sides thereof to retain theindicator plunger in position indicating the smallest diameterperceivable by the gage during its operation, In other words, theindicator is only operated by the downward movement of the plunger andwill not reverse its movement of operation except under the influence ofmanual pressure applied to the lower end of the plunger extension, whichis provided with a push button 30 for that purpose.

The gage head 24 and tube 2|, together with parts carried thereby, ishingedly supported on the end of a vertically swingable arm 3|, theinner end of which arm is mounted on a spring housing 32 internallybiased by means (not shown) to more or less balance the weight of thearm 3| and parts carried thereby; 33 indicating a support for thespindle of the said spring housing, which sup-port may be attached toany stationary part of the grinding machine which is convenient. Thedescribed arrangement admits of the gage mechanism including the caliperframe l8 being swung into and out of operative relation to the work tofacilitate unobstructed removal and replacement of work wheneverdesired.

The cam element E3 of the adaptor H is provided with flats ordepressions 34 coinciding with the high points of the piston periphery,as shown; and mounted on the headstock H) of the machine is a bracket 35carrying a pin 36 on which a follower arm 31 is hingedly mounted forvertical lifting against the resistance of a spring 38. The outer end ofthe said arm 31 carries a follower roller 3Q positioned to ride theperiphery of the said cam element l3 whereby the said follower arm 31will be slightly depressed by the spring 33 when the roller 39 passesover one or other of the flats 34 of the said cam element. This followerarm 31 has projecting from one side thereof a block 40 provided on itsupper surface with an insert 4| of wear-resistant material.

It will be noted that the follower arm 31 is positioned behind thecaliper frame l8, as viewed in Figure 1, and this caliper frame carriesa similarly swingable caliper jaw 42 which is provided with a shoe 43beneath its outer free end to rest upon the work when it is sopermitted.

However, this movable caliper jaw 42 is provided with a rearwardlyextending block 44 which carries a vertically adjustable stop 45extending over the wear-resistant insert 4| of the cam follower block43, as clearly shown in Figure 2.

Thus, when the lower end of this stop 45 is closely spaced from the topof the insert 4| with the roller 39 riding one of the flats 34 of thecam element [3, the raising of the follower arm 31, when the said rollerleaves such fiat and thereupon travels the cam surface of greaterdiameter, will cause the said block 40 to strike beneath the stop 45 andthus raise the movable caliper jaw 42. This raising of the jaw 42 causesthe shoe 43 thereof to be spaced above the surface of the piston or workas indicated at c in Figure 2.

While the caliper jaw 42 is so raise-d (which is throughout almost theentire cycle of rotation of the work), the gage rod 22 of the gageproper is also raised out of operative contact with the plunger 26 ofthe indicator 21. It is only through the very brief interval duringwhich the roller 39 traverses one or other of the flats 34 of the camelement that the shoe 43 of the movable caliper jaw is permitted tocontact the work and, with' the setting shown, this contact would belimited to the high points in the periphery of Work.

By reason of the braking effect imposed on the plunger extension 28 ofthe indicator 21, the

only indicating motion transmitted to the indicator mechanism would bethat representing the reduced radial distance of the high point of thepiston, resulting from the grinding which has taken place since themovable caliper arm was previously released, by the action of thefollower arm '21, to perform its checking function. Where this releaseis effected normally once, or twice, in each revolution of the work, thechange in radial dimension would be extremely slight and not readilyperceptible to the eye in reading the indicator, but the series of veryslight and progressive timed downward movements of the gage plunger 22,resulting from the checking motions of the movable caliper jaw 42, wouldeventually show that reading on the indicator which would warn that thegrinding was complete or close to completion as the case may be.

Figure 1 also shows how the arrangement lends itself to use with anelectric gage such as of the type disclosed in United States Patent No.2,267,- 559 of applicant granted to me December 23, 1941, this beingshown schematically and for simplicity in the present drawings as amovable switch plate 46 adapted to close contacts 41 upon the gageplunger descending to the position of complete grinding, whereupon thecircuit is closed through the solenoid 48 to open a switch 49 andthereby cut off current through the grinding machine motor l5 to stopfurther grinding action of the machine to which it is applied.

This invention may be developed within the scope of the following claimswithout departing from the essential features of the said invention, andit is desired that the specification and drawings be read as beingmerely illustrative of a practical embodiment of the same and not in astrictly limiting sense.

What I claim is:

1. In a production gage of the type described, in combination,work-rotating means, work calipering means including a movable caliperjaw, a work-checking device, means coupling said device with said jawfor transmitting movements of said jaw thereto to determine completionof the grinding of the work, a cam, and a cam-operated member adapted tomove said jaw out of contact with the work except at timed intervalsdetermined by the rotation of said cam.

2. In a production gage of the type described, in combination,work-rotating means, said means including a cam, work calipering meansincluding a movable caliper jaw, a work-checking device, means couplingsaid device with said jaw for transmitting movements of said jaw theretoto determine completion of the grinding of the work, and a movable jawactuating member adapted to operation by said cam to move said jaw outof contact with the work except at timed intervals determined by therotation of said cam.

3. In a production gage of the type described, in combination,work-rotating means, work calipering means including a movable caliperjaw, a work-checking device, means coupling said device with said jawfor transmitting movements of said jaw thereto to determine completionof the grinding of the work, a cam, and a cam-operated member positionedto engage and lift said jaw out of contact with the work except at timedintervals in the rotation thereof.

4. In a. production gage of the type described,

in combination, work-rotating means, work-calipering means including amovable caliper jaw, a work-checking device, means coupling said devicewith said jaw for transmittin movements of said jaw thereto to determinecompletion of the grinding of the work, a cam, a movable cam follower,and adjustable means through which lifting of said follower by said cammay be transmitted to said movable caliper jaw.

5. In a production gage of the type described, in combination,work-rotating means, work-calipering means including a verticallyswingable caliper jaw, a work-checking device, means coupling saiddevice with said jaw for transmitting movements of said jaw toward theaxis of the work to said device, a, cam, a follower arm for said cam,and means for causing said follower arm when lifted by said cam to liftsaid caliper aw.

6. In a production gage of the type described, in combination,work-rotating means, work-calipering means including a verticallyswingable caliper jaw, a work-checking device, means coupling saiddevice with said jaw for transmitting movements of said jaw toward theaxis of the work to said device, a cam, a follower arm for said cam, andadjustable means for causing said follower arm when lifted to apredetermined extent by said cam to lift said caliper jaw.

7. In a production gage of the type described, in combination,work-rotating means, work-calipering means including a verticallyswingable caliper jaw, a work-checking device, means coupling saiddevice with said jaw for transmitting movements of said jaw toward theaxis of said work to said device, a cam, a follower arm for said cam,said cam having a circumferentially localized dwell timed to pass undersaid follower arm as a point of given finish radius of the work passesbeneath said jaw, and means for causin said follower arm when lifted bysaid cam to lift said caliper jaw.

8. In a production gage of the type described, in combination,work-rotating means, work-calipering means including a verticallyswingable caliper jaw, a work-checking device, means coupling saiddevice with said jaw for transmitting movements of said jaw toward theaxis of said work to said device, a cam, a follower arm for said cam,means for causing said follower arm when lifted to lift said caliperjaw, said cam having a cir-cumferentially localized dwell timed to passunder said follower arm as a point of given finish radius of the workpasses beneath said jaw, and adjustable means for causing said followerarm when lifted by said cam to a predetermined extent to lift saidcaliper jaw.

SHUBEL A. FOSTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,834,231 Whitman Dec. 1, 1931FOREIGN PATENTS Number Country Date 604,377 Germany Oct. 19, 1934

